Refrigeration Machine Compressor Cooling Using Single Expansion Valve
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Solution Overview
Problem
Existing refrigeration machines with multiple compressors require complex and costly compressor cooling systems, involving individual expansion valves for each compressor, which increases production costs and control effort, and can lead to compressor damage due to overheating.
Innovation Solution
A method where a single second expansion valve is used to expand and partially evaporate refrigerant, which is then fed to multiple compressors for cooling, eliminating the need for individual expansion valves and simplifying control efforts by regulating the refrigerant's overheating and superheating based on detected pressure and temperature values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual expansion valves are provided for each compressor, then each compressor can be cooled according to its operating state, but the device complexity and production costs increase
Solution Approach 1:
Multiple expansion valves for individual compressors are merged into a single common expansion valve that serves all compressors. The refrigerant is expanded once at the common valve and then distributed to multiple compressors through a distribution manifold, reducing the total number of valves from n (one per compressor) to just one.
Solution Approach 2:
The single common expansion valve performs the expansion function for all compressors simultaneously, making it a universal component that replaces multiple specialized valves. This multi-functional approach maintains cooling effectiveness for each compressor while eliminating redundant components.
2Ease of operation
If individual expansion valves are provided for each compressor, then precise control of refrigerant flow to each compressor is achieved, but the control effort and production costs increase
Solution Approach 1:
The control functions of multiple individual expansion valves are merged into a single control system for the common expansion valve. The control unit receives feedback from temperature sensors on each compressor and adjusts the opening of the single valve to balance refrigerant distribution, simplifying the control architecture while maintaining precision.
Solution Approach 2:
Temperature sensors on each compressor provide feedback to the control unit, which adjusts the common expansion valve opening to maintain optimal cooling for each compressor. This feedback mechanism enables precise control of total refrigerant flow to match the aggregate cooling needs of all compressors.
3Productivity
If compressors are operated at the limit of their capacity, then the cooling performance is maximized, but the compressor temperature exceeds maximum permissible limits and damage occurs
Solution Approach 1:
The system performs preliminary cooling of the refrigerant through the common expansion valve and subcooler before it enters the compressors. This advance cooling ensures that even when compressors operate at maximum capacity, the refrigerant entering them is sufficiently cold to prevent discharge temperatures from exceeding safe limits.
Solution Approach 2:
The system changes the temperature parameter of the refrigerant by expanding it through the common expansion valve and cooling it in the subcooler before compression. This parameter modification allows compressors to operate at high capacity while maintaining safe discharge temperatures through controlled refrigerant temperature entering the compression process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces production costs, simplifies control efforts, and effectively prevents compressor overheating, thereby extending compressor service life and reducing the risk of damage.
Implementation Method 1
cooled by the subcooler (18)
Implementation Method 2
at least partially evaporated by the subcooler (18)
Implementation Method 3
expanded by means of a second expansion valve (24)
Implementation Method 4
The compressors compress the refrigerant vaporized in the evaporator and eject the compressed refrigerant at their outlets as so-called compressed gas, which has an increased pressure and an increased temperature
Implementation Method 5
the refrigerant vaporized in the evaporator
Data Source
Figure 1
AI summary
The method involves branching-off the liquid refrigerant between a condenser (16) and a sub-cooler (18), from a closed circuit (11), The liquid refrigerant is expanded by an expansion valve (24), and is partially vaporized by a vaporizer (22). The partially vaporized liquid refrigerant is supplied to the compressors (12,14) for cooling by the sub-cooler. An independent claim is included for a refrigerating machine.